Labour leadership contender Ed Miliband has said he can "unite" the party and win back the voters it has lost.
He told BBC One's Andrew Marr show that deciding to take on brother David for the leadership had been one of the hardest decisions of his life.
The two Milibands are the first and so far only Labour MPs to have thrown their hat into the ring.
They have both promised to reconnect the party with voters and move beyond the Blair/Brown era.
Ed Miliband refused to be drawn into commenting on why he thought he would make a better leader than his older, and better known, brother.
'Best friend'
The former energy and climate change secretary told Andrew Marr: "I would try and bring my sense of idealism and values, my sense of empathy and my ability to reach out and understand people's lives and my ability to unite the party."
Asked whether he was "more human" than his older brother, he said: "Honestly that's all rubbish, one thing I'm not going to do in this contest is mischaracterise my brother because I think he's got an enormous contribution to make to our country."
Ed Balls will make a great leader of our party, but the reality is we are not going to rush into this
He said Labour had lost the support of traditional Labour voters on issues such as immigration - but had also "lost the voters that Tony Blair attracted to our party in 1997 and I would want to win them back and I would make that a very important part of my leadership".
The two brothers have pledged to work together regardless of who wins the leadership.
David Miliband told the Observer it was time to for the party to move on from the New Labour, saying tensions between Blairites and Brownites were "gone and over".
"Anyone who thinks that the future is about re-creating New Labour is wrong. I think we've got to use this period to decisively break with that. What I'm interested in is Next Labour."
'Great talents'
Former Olympics Minister Tessa Jowell is the latest senior Labour figure to throw her weight behind David Miliband, saying he is the candidate with "real credibility as future prime minister".
But she said it was important to have a "wide range of candidates" and as "two of the great talents of their generation" it was natural that David and Ed Miliband would both want to stand.
Former transport minister Sadiq Khan told the programme he supported Ed Miliband because he had the "vision, skills and the energy to be a fantastic leader of our party but also of our country".
Other Labour MPs to back the younger Miliband brother include ex Cabinet minister Hilary Benn, Stephen Pound, Andy Slaughter, Linda Riordan and former ministers Ian Lucas, Helen Goodman and several backbenchers.
David Miliband remains favourite at the bookmakers to replace Gordon Brown at the head of the party, but odds on Ed have been cut since he announced his decision to stand.
Two newspaper polls also suggest David would be the most popular choice among the public, with a third of voters backing him for the leadership.
It is expected the Unite union, which wields significant voting power in the leadership contest, will back Ed Balls, if he decides to stand but the union's political director Charlie Whelan insisted it had not yet decided who to back.
Mr Whelan told Andrew Marr: "The political committee of the union hasn't met yet and they want to consult the members widely. We are not going to decide to support one candidate or another and tell the members to vote for them. It just doesn't work like that."
He added: "Ed Balls will make a great leader of our party, but the reality is we are not going to rush into this. Some people want a coronation but we have got three or four excellent candidates."
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